Control system for clothes dryers



Nov. 4, 1958 Filed May 9, 1956 2,858,619 CONTROL SYSTEM FOR CLOTHES DRYERS Philip G. Hughes, Anchorage, Ky., assignor to General Electric Company, .a corporation "of New York Application May 9, 1956, s i NQ 3 7 8 Claims. 01. 34-45 My invention relates to domestic' 'clothesdrying machines and more particularly 'to an improved control.

system for controllingthe operation of such machines.

A door switch is ordinarily provided in domestic clothes dryers in order to interrupt the rotation of'the drive motor and the tumbling drum whenever the door is opened. This is done in order to provide operator safety in the machine. Concurrently with the de-energization of the drive motor the heaters are also orclinarilydeenergized in order to prevent overheating of the machine,

the door re-energizes the drive motor, the heater and the timer so that the machine resumes full operation. It is more desirable, however, to provide a separate manual switch which must be operated after the door is closed in order to start the machine up again. This additional manual switch is desirable because sometimes the house-- wife may not reclose the door immediately after opening it. Rather she may reach into the machine, feel the clothes, decide they are dry and remove them from the machine leaving the door open. She may then forget to turn the timer to the olt position so that the machine sits there idle, but in a condition such that itwill start again just as soon as the door is closed. This presents an undesirable condition because the door may be closed sometime later by someone other than the operator without any consideration of what is in the dryer and where the timer is set. In other words it may result in the dryer being placed in operation when it is not desirable for it to go into operation. For example the operator may have left some of the clothes in the drum preparatory to sprinkling them and if the dryer were to go back into operation, scorching of these clothes might be caused. Also a child might place some foreign object in the dryer and then slam the door resulting in serious damage either to the object or to the machine itself.

It is an object of my invention to provide a new and V improved clothes dryer control system including a manual start switch which must always be operated to place the machine in operation, both initially and after the opening and closing of the dryer door. 7

Another object of my invention is to provide an improved clothes dryer control system in which the drive motor is locked out of operation by a speed responsive switch whenever the dryer door. is opened, and can be placed back into operation only by the operation of a .manually controlled switch. v t

A further object of my invention is to provide a clothesdryer control system including a manual start switch, in

2,858,619 Patented Nov. 4, 1958 lice which the start switch is connected and arranged that no holding relays or the like are required in the system.

' by the drive motor.

In carrying out my invention I provide a clothes dryer having a clothes tumbling drum and a drive motor for driving the tumbling drum. The drum and the drive motor are enclosed within a cabinet which includes a door for access to the drum. By my invention 1 provide within this dryer a new and improved control system for energizing the drive motor from a power supply. The con trol system includes a door switch which is operated by the door and a speed responsive switch which is operated The door switch is open when the door is open and is closed when the door is closed, and the speed responsive switch is closed when the motor is at operating speed and open when the motor is at rest. These two switches are arranged in a drive motor circuit so that the drive motor is energized from the power source through them. Connected in this manner the drive motor is de-energized whenever the door is opened and is then locked out by the opening of the speed responsive switch as it comes to rest. In order to continue the drying operation after the door is reclosed, the conswitch sothat the manually operable switch may be released. My new and improved control system thereby provides for the initiation of the dryer operation at all times by means of a manual start switch, without any expensive relays, holding coils, or the like, being required. The subject matter which I regard as my invention is particularly pointed out and distinctly claimed in the coneluding portion of this specification. My invention, however, both as to organization and method of operation,

together with further objects and advantages thereof, may be best understood by reference to the following description taken in conjunction with the accompanying drawing in which:

Fig. 1 is a perspective view of a clothes dryer including partially broken away and partially in section to illustrate details of construction; and v Fig. 2 is a schematic diagram of a control system embodying my invention in one form thereof.

Referring now to Fig. 1 I have shown therein a clothes dryer 1 which is illustrative of the various clothes dryers in which my new and improved con trol system may be used. The dryer 1 includes a rotatable drum or basket 2 which is mounted for rotation about a generally horizontal axis. The basket 2 is disposed within an outer enclosing cabinet structure 3, and aligned openings 4 and 5 are provided respectively in the front walls of the basket and the cabinet structure for the loading and unloading of clothes from the basket. The openings 4 and 5 are flanged as shown to prevent clothes from dropping down between the basket and the cabinet. A door 6 hingedly mounted on the cabinet closes the opening 5 during the operation of the machine.

For rotating the drum or basket 2 during the opera- 7 tion of the dryer there is provided an electric motor 7 which is connected to the basket by a suitable drive belt 8. The pulleys (not shown) mounting the belt are so arranged that the basket 2 is driven at a suitable speed for tumbling articles of clothing therein. The basket 2 preferably includes upstanding ribs on the upper sur-,

Then after the drive motor comes up to speed, it is locked in bythe closing of the speed responsive The air moving means comprises a centrifugal blower 9 which is driven by motor 7 by means of a direct coupling It The blower 9 draws in air from the surrounding room through a conduit 11 which leads from a.

screened air inlet opening 12 in the toeboard 13 of the cabinet.

The air drawn in by the blower 9 is discharged through an opening 14 at the top thereof into a passage 15 which is separated from the rotating basket by a baffle 16. As shown, the baifie 16 extends upwardly from the base of the machine to a point in the general vicinity of an electric heating element 17 mounted at the top of the machine, the bafile 16 being curved arcuately around the perforated side wall 18 of the drum for a portion of its length. The air discharged from the blower 9 flows upwardly through the passage 15 and passes outwardly therefrom across the electrical heating element 17. The air still under pressure from the blower flows downwardly through the foraminated cylindrical wall 18 of the basket. The air moves through the basket and the articles of clothing being tumbled therein and next passes into a collecting chamber 19 lying beneath the basket 2 on the opposite side of the baffle 16 from the passage 15. From the chamber 19 the air is discharged out of the cabinet into the surrounding room through an appropriate lint trap structure 26 mounted in the toeboard 13.

The clothes dryer 1 is intended for use both as a drying means and as a clothes sprinkling means. When the machine is to be used as a clothes drying machine, the heater 17 is energized along with the drive motor 7. Thus the air discharged from the passage 15 absorbs heat from the heater 17 as it passes thereover. The heated air then extracts moisture from the clothes being tumbled in the drum as it passes therethrough. The heating element, -however, is not energized when the dryer isbeing used as a sprinkling means. Thus the air passing through the drum is not heated and does not extract moisture from the clothes. Any suitable means may be used to sprinkle the clothes during the sprinkling operation, but it is preferred to use a container which may be mounted on the drum 2 so as to discharge water slowly as the drum rotates. A suitable container for this purpose is shown and described in the copending application of Eugene G. Olthius S. N. 430,794 filed May 19, 1954, and assigned tothe same assignee as the present invention.

Referring now to Fig. 2 l have shown therein a control system for the dryer 1, this control system embodying my invention in one form thereof. system includes a door switch 21 Whose operation is controlled by means of a door 6 of the dryer. The switch 21 includes a set of contacts 22 which are closed whenever the door is closed and which are opened whenever 'the door is open. These contacts 22 are so connected in the control system that they de-energize the drive motor 7 whenever the door is open. The contacts however do not re-energize the mot-or circuit by themselves when the door is closed. Rather for the motor to be started again a manually operable push button start switch 23 must first be depressed. This start switch,23, which is spring biased to the normally open position, is mounted on the backsplasher 24 of the dryer cabinet 3 (Fig. 1) so that it is out of reach of small children and therefore relatively safe from tampering by them.

For controlling the drive motor in this manner, the contacts 22 of the door switch and the manually operable switch 23 are both connected in the energizing circuit for the drive motor 7. The control system as a whole is energized from a power supply comprising conductors 25 and 26 and a neutral line 27, and the drive motor circuit, specifically, is energized between the supply conductor 26 and the neutral line 27. The illustrated control system is particularly intended for use with a voltage This control 'It will be understood, however, that my invention is not necessarily limited to control systems for use with a 220 volt three wire supply, but rather may be applied to control systems for use with any available domestic power supply, for example a 110 volt two-wire supply.

Cit

Commencing with the neutral line 27 the drive motor circuit extends through the contacts 22 of the door switch, a fusible link 28, a conductor 29 and a thermal type overload protector 30 to the start and run windings 31 and 32 of the motor 7. The start and run windings are in turn both connected to a line 33 which leads to the normally open start switch 23, the run Winding 32 being directly connected to the line 33 and the start winding 31 being connected, thereto through a set of normally closed contacts 34 of a motor speed responsive switch 35. The contacts 34 are closed so long as the motor 7 is at rest but when the motor comes up to speed the speed responsive switch is operated by centrifugal mechanism 36 so as to open the contacts 34 and close a normally open set of contacts 37. It will be noted that the contacts 37 of the'speed responsive or centrifugal switch are connected in parallel across the start switch 23 by means of conductors 38 and 39. The purposeof this parallel connection is explained hereinafter;

From the manually operable switch 23 the motor circuit continues through a line 40 to a switch 41 of a sequence control mechanism/12. This sequence control mechanism 42 is driven by means of a timer motor 43 and includes suitable actuating means such as a cam for opening and closing the switch 41. The switch 41 is closed by the timer mechanism whenever the machine is in operation, and in fact, .the operation of the dryer is terminated when themechanism does open the switch 41. The timer mechanism may be suitably adjusted by mean of a manual control knob-44 to provide the desired time of operation. No particular timer mechanism is illustrated since such mechanisms are well known to the art and. any suitable one may be used. From the switch 41 the drive motor circuit is completed to power line 26 through a conductor 45.

In order to energize the drive motor 7 through this circuit and thereby place the dryer in operation, the control knob 44 is first rotated so as to close the switch 41 of the timer mechanism. Assuming the door 6 to be closed so that the contacts 22 of the door switch are closed, the circuit is then ready for energizing the drive motor. To complete the circuit and energize the drive motor it is then necessary to close the manual push button switch 23. The closing of the switch 23 energizes both the start and run windings of the drive motor, the run winding being energized directly between the motor protector 30 and the line 33 and the start winding being energized between the motor protector and the line 33 through the contacts 34 of the motor centrifugal switch 35,- As soon as the motor comes up to speed, the contacts 34 of the centrifugal switch are opened, de-energizing the start winding. Simultaneously the contacts 37 of the switch are closed, and the closing of the contacts 37 shorts out the start switch 23 through the conductors 38 and 39. This locks in the motor and the start switch 23 may thereupon be released. In other words the run winding 320E the motor is now energized through the contacts 37 and the lines 38 and 39 so that it will continue the motor in operation without the start switch being closed.

The'energization of the drive motor through the contacts 37 continues until such time as either the door switch or the timer operated switch 41 is opened. The

opening of either of these switches, of course, breaks the motor circuit and tie-energizes the motor 7. The

rnotor being ,de-energized thereupon comes to a stop, opening the contacts 37 of the centrifugal switch 35 and closing the contacts 34.

" The opening of the contacts 37, in accordance with my invention, breaks the drive motor circuit at a second point and thereby locks out the drive motor 7 even if the timer operated switch 41 or the door switch 21 should be immediately reclosed. The only way that the drive motor can be re-energized once either of these. switches is opened is for the manually operated switch 23 to be closed. Even after both of these switches are reclosed, the centrifugal switch contacts 37 still maintain the drive motor circuit open untilthe manually operated switch 23 is closed. The closing of the switch 23, as exlained above, shorts out the contacts 37 and thereby completes again the drive motor circuit to place the drive motor back in operation. Once the motor comes up to speed, the contacts 37 are closed once more by. the centrifugal mechanism and themanual switch may be released. i i

I This arrangement of the manually operated switch 23 is particularly intended to prevent accidental restarting of the dryer when the operator opens the dryer door during the middle of the cycle in order to check the condition of the clothes. The operator may open the -door 6 during the middle of the cycle in order to feel cides that the clothes have dried sufficiently, she will.

normally remove them from the machine, perhaps leaving the door open. In this case since the timer has not yet opened switch 41, the drive motor circuit is still conditioned for operation. My new and improved control system however prevents accidental restarting of the dryer in this situation even if the door should then be slammed or otherwise closed at some later time. Since the manually operated switch 23 must be closed in addition to the closing of the door switch, 'any accidental starting of the dryer is completely avoided. Thus clothes may safely be removed from the dryer at any point during the drying operation without turning the timer tothe off position.

"When the machine 1 is acting as a clothes dryer the heater 17 is energized concurrently with the drive motor. The heater 17 specifically is energized'across the power supply conductors 25 and 26. Commencing with the conductor 25, the heater circuit extends through the heater itself and a conductor 46 to the normally open contacts 47 of a second motor operated, speed responsive switch 48. Preferably and as shown this switch 48 is operated by the same centrifugal mechanism 36 as the switch 35. From the contacts 47 the heater circuit continues through a line 49, a heater cycling thermostat 50, and line 51 to a switch 52 of the sequence control mechanism 42. This switch 52 like the switch 41 is controlled by means of a cam operated by the timer-motor 43. From the switch 52 the heater circuit is completed through the line 45 to the power supply conductor 26. Energized through this circuit it will be seen that the heater 17 will be energized so long as the centrifugal switch 48 and the timer operated switch 52 are closed. If either of the switches are opened, the heater will be de-energized. The heater cycling thermo-' stat 50 also is effective to de-energize' the heater whenever the temperature within the dryer rises above a certain predetermined suitable level for drying clothes. The cycling thermostat 50 may be positioned at any suitable place within the dryerbut preferably it is positioned near the top of the dryer in the path of the air after it leaves the heater and before it enters the tumbling drum.

The timer mechanism 42 is preferably so arranged that it includes two separate operating ranges for the dryer, these ranges being separated by off positions. In one of these ranges both switches 41 and 52 are closed so that boththe drive motor and the heater are energized. This of course results in a clothes drying operation. In the second of these ranges however only the drive motor switch 41 is closed. ,This results in a clothes tumbling operation without heat. This operation may be used for sprinkling clothes if the aforementioned sprinkling container is placed within the tumbling druin, or it maybe used to fluff previously dried clothes; I I

Assuming that the timer mechanism 42 is adjusted by the means of the knob 44 so that both switches 41 and 52 are closed, the heater circuit will then be energized concurrently with the drive motor circuit. However the heater 'circuit is not energized immediately as soon as the manually operated switch 23 is depressed to, start the dryer. Rather'the heater circuit is not ,closed until such time as the centrifugal switch mechanism closes the contacts 37 and 47. In other Words the heater circuit is not completed until the centrifugal switch mechanism locks in the drive motor circuit. Once the heater circuit is closed by the'centrifugal switch 48, it then remains closed under the control of the cycling thermostat 50 until either the sequence control switch 52 or the centrifugal switch contacts 47 are opened. Normally unless the door 6 is opened, the centrifugal switch contacts 47 will remain closed throughout the drying operation until the timer mechanism opens the switch 52. The switch 52 is preferably opened a short time prior to the opening of the switch 41 to provide a machine cool-down period during which cool air is blown through the dryer to cool both the clothes and the machine itself down to a suitable temperature for the removal of the clothes.

If however the door 6 should be opened, then the heater circuit will be de-ene'rgized by the centrifugal switch 48. The opening of the door, of course, de-energizes the drive motor in the manner described above and as the drive motor comes to a stop, the contacts 47 are opened. The opening of the contacts 47 breaks the heater circuit and thereby prevents any heating 'of the machine and the clothes until such time as the drive motor is placed back in operation. In other words due to the action of the centrifugal switch 48, the heater is locked out just like the drive motor until such time as the door 6 is reclose'd and the manual switch 23 is depressed.

In order to time the length both of the drying operation and of the clothes tumbling operation without heat, the timer motor 43 is energized continuously during both operations. When the timer has run during the drying operation for the length of time pre-selected by the operator, it then opens the switches 41 and 52 to terminate the operation of the machine, the switch 52 being opened slightly before the switch 41 to provide the machine cool-down period mentioned above. During the clothes tumbling operation without heat, the switch 52 is of LCOLIISfi never closed so that in that operation the timer merely opens the switch 41 to terminate the operation.

The timer motor 43 like the drive motor 7 is energized between the neutral line 27 and the supply conductor 26. Starting with the neutral line 27 the timer motor circuit extends through the contacts 22 of the'door switch and aline 53 to the timer motor itself. From the other side of the timer motor the circuit passes through a line 54 to the switch 41 of the timer and from there it is complcted to the supply conductor 26 through the line 45. Energized through this circuit it will be seen that the timer motor is energized whenever the door switch 21 and the timer switch 41 are closed. When the timer switch 41 opens at the end of the machine operation, the timer motor is de-energized at the same time as the drive motor. Similarly when the door 6 is opened, the timer motor will be de-energized concurrently with the drive motor. However, the operation of the timer motor does not depend upon the manually operated switch 23 when the door 6 is reclos'ed. Rather as soon as the door is reclosed, the timer motor will begin to run again whether or not the manually operable switch 23 is closed.

This is desirable since it results in the timer motor running to the o position, Where it opens the switch 41, Whenever the door is closed. This of course completely de-energizes both the timer circuit and the drive motor circuit. The machine then cannot be placed back in operation merely by closing of the switch 23. Rather the timer must be adjusted first by the dial 44 so as to close the switch 41. The automatic running of the timer to the off position when the door is closed thereby prevents a later accidental starting of the dryer if the start switch should be bumped or otherwise inadvertently operated. In other words if the clothes are removed and the door reclosedduring themiddle of the cycle, the timer motor then times the cycle out without the machine itself operating whereby the machine cannot he accidentally started at some later time merely by the pushing of the start button.

From the above it will be seen that I have provided a new and improved control system for a clothes dryer, in which a manual start button must always be depressed in order to place the machine in operation. If the door of the dryer should be opened during the drying operation, a door switch automatically interrupts the operation of the dryer. However, the mere closing of the door does not start the dryer up again. Rather the start button must be depressed after the door is closed in order to place the dryer back in operation. The start button must also be depressed at the beginning of the dryer operation to start the dryer operation in the first place. The control system is so arranged that this desirable start button feature is provided without any holding relays, coils or the like being required. In my preferred arrangement the motor speed responsive or centrifugal switch automatically locks in the motor circuit after the start button has depressed and then automatically locks out the circuit whenever it is de-energized by any other means such as the door switch. In my preferred embodiment the centrifugal switch and the start switch are, of course, connected in electrical parallel to effect that result.

While in accordance with the Patent Statutes I have described what at present'is considered to be the preferred embodiment of my invention it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and I, therefore, aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a clothes dryer having clothes tumbling means, a cabinet enclosing said tumbling means and including a door for access to said tumbling means, and a drive motor for driving said tumbling means, a control system for energizing said drive motor from a power supply, comprising a door switch operated by said door, said door switch being opened when said door is open and closed when said door is closed, a speed responsive switch operated by said drive motor, said speed responsive switch being closed when said motor is in operation and being open when said motor is at rest, a drive motor circuit for energizing said drive motor from said power supply through said door switch and said speed responsive switch, said drive motor circuit being locked out by the opening of said speed responsive switch whenever said motor is tie-energized by the opening of said door switch, and a manually operable switch for r e-energizing said drive motor to continue the drying operation after the opening and reclosing of the said door, said manually operable switch being connected across said speed responsive switch whereby the closing of said manually operable switch shorts out said speed responsive switch and energizes said drive motor.

2. Ina clothes dryer having clothes tumbling means,

8 a cabinet enclosing said tumbling means and including a door for access to said tumbling means, and a drive motor for driving said tumbling means, a control system for energizing said drive motor from a power supply, comprising a control mechanism having a drive motor switch, a door switch operated by said door, said door switch being open when said door is open and closed when said door is closed, a speed responsive switch operated by said drive motor, said speed responsive switch being closed when said motor is in operation and being open when said motor is at rest, a drive motor circuit for energizing said drive motor from said power supply through said drive motor switch of said control mechanism, said door switch and said speed responsive switch, said drive motor circuit being locked out by the opening of said speed responsive switch whenever said motor is de-energized by the opening of said drive motor switch or said door switch, and a manually operable start switch for initiating the operation of said drive motor to start the drying operation and for re-starting said motor after any opening and reclosing of said door to continue the drying operation, said manually operable switch being connected in parallel with said speed responsive switchwhereby the closing of said manually operable switchshorts out said speed responsive switch and energizes said drive motor until said speed responsive switch recloses and locks in said circuit.

3. In a clothes dryer having clothes tumbling means, a drive motor for driving. said ttunbling means, and a cabinet enclosing said tumbling means and said drive motor and including a door foraccess to said tumbling means, a control system for energizing said drive motor from a power supply, comprising a timer mechanism having a timer motor and a drive motor switch operated by said timer motor, a door switch operated by said door, said door switch being open when said door is open and closed when said door is closed, a speed responsive switch operated by said drive motor, said speed responsive switch being closed when said motor is in operation and being open when said motor is at rest, a drive motor circuit for energizing said drive motor from said power supply through said drive motor switch, said door switch and said speed responsive switch, said drive motor circuit being locked out by the opening of said speed responsive switch whenever said motor is deenergized by the opening of said drive motor switch or said door switch, a manually operable start switch for initiating operation of said drive motor, said manually operable switch being connected across said speed responsive switch whereby the closing of said manually operable switch shorts out said speed responsive switch and energizes said drive motor, and a timer motor circuit for energizing said timer motor through said door switch and said motor switch thereby to energize said timer whenever said door and said drive motor switch are closed regardless of whether said manually operable switch is operated.

4. In a clothes dryer having a clothes tumbling means, a drive motor for driving said tumbling means, a cabinet enclosing said tumbling means and said drive motor, said cabinet including a door for access to the tumbling means and having a top panel and a backsplasher extending upwardly from said top panel, a control system for energizing said drive motor from a power supply, comprising a control mechanism having a drive motor switch, a door switch operated by said door, said door switch being open when said door is opened and closed when said door is closed, a speed responsive switch operated by said drive motor, said speed responsive switch being closed when said motor is in operation and being open when said motor is at rest, a drive motor circuit for energizing said drive motor from said power supply through said drive motor switch, said door switch and said speed responsive switch, said drive motor circuit being locked out by the opening of said speed responsive 9 switch whenever said motor is de-energized by the opening of said drive motor switch or said door switch, and a manually operable start switch mounted on said backsplasher for initiating operation of said drive motor, said manually operable switch being connected across said speed responsive switch whereby the closing of said manually operable switch shorts out said speed responsive switch and energizes said drive motor.

5. In a clothes dryer having a clothes tumbling drum, a heater for heating the clothes in said drum, a drive motor for driving said tumbling means, and a cabinet enclosing said drum, said heater and said drive motor and having a door for access to said drum, a control system for energizing said drive motor and said heater from a power supply, comprising a timer mechanism having a drive motor switch and heater switch, a door switch operated by said door, said door switch being opened when said door is open and closed when said door is closed, first and second speed responsive switches operated by said drive motor, both said first and second speed responsive switches being closed when said motor is in operation and being open when said motor is at rest, a heater circuit for energizing said heater through said heater switch and said first speed responsive switch, a drive motor circuit for energizing said drive motor from said power source through said drive motor switch, said door switch, and said second speed responsive switch, said heater circuit and said drive motor circuit both being locked out by the opening of said speed responsive switches whenever said motor is deenergized by the opening of said door switch, and a manually operable start switch for starting said drive motor at the beginning of the drying operation and for restarting said drive motor after any opening and reclosing of said door to continue said drying operation, said manually operable switch being connected across said second speed responsive switch whereby the closing of said manually operable switch shorts out said second speed responsive switch to energize said drive motor.

6. In a clothes dryer having clothes tumbling means, a drive motor for driving said tumbling means, said drive motor having a start winding and a running winding, and a cabinet enclosing said tumbling means and said drive motor and including a door for access to said tumbling means, a control system for energizing said drive motor from a power supply, comprising a control mechanism having a drive motor switch, a door switch operated by said door, said door switch being open when said door is open and closed when said door is closed, a drive motor circuit for energizing said drive motor through said drive motor switch and said door switch, said circuit including a manually operable start switch connected for energizing both of said start and run windings to initiate motor operation and speed responsive switch means for de-energizing said start winding and locking in said running winding when said motor comes up to speed, said speed resposive switch means being arranged to lock out said drive motor upon the subsequent opening of said door switch, whereby said start switch must be again operated to restart said motor.

7. The combination of claim 6 wherein said dryer includes a heater, and said control system includes second speed responsive switch means operated by said motor, said second speed responsive switch means being normally open when said motor is at rest and being closed when said motor is in operation, a heater switch operated by said control mechanism, and a heater circuit including said second speed responsive switch means and said heater switch for energizing said heater.

8. In a clothes dryer having clothes tumbling means, a drive motor for driving said tumbling means and a cabinet enclosing said tumbling means and said drive motor and including a door for access to said tumbling means, a control system for energizing said driving motor from a power supply, comprising a timer motor, a door switch operated by said door, said door switch being open when said door is open and closed when said door is closed, a drive motor circuit for energizing said drive motor, and a timer motor circuit for energizing said timer motor, both of said circuits including said door switch and switch means operated by said timer, and said drive motor circuit additionally including lock-out switch means and a manual start switch, said lock-out switch means being arranged to lock out said drive motor whenever said drive motor is de-energized, and said start switch being arranged to short said lock-out switch means to re-energize said drive motor, said timer motor circuit being independent of said lock-out switch means and said start switch.

References Cited in the file of this patent UNITED STATES PATENTS 2,701,421 Erickson et al. Feb. 8, 1955 2,743,532 Steward May 1, 1956 

